I hate to say this, but if you don’t have wars it could be that you wind up with an excess of military aged males and that leads inevitably to a lot of political instability. Ever hear of the job title “chicken sexer”? They check all the baby chicks for their sex and then break all the males necks and throw’em in a bucket.
Obviously you ‘missed my last line ...<: <: <:
However, it is one way to keep the population trimmed down.
And I do believe that is/was the Bushido code....